West Australian government-owned energy generator and retailer Synergy said site works have started on a new 200 MW/800 MWh big battery being built alongside the 100 MW/200 MWh Kwinana battery energy storage system that is currently working through its final testing and commissioning process.

The 200 MWh first stage of the Kwinana battery project is expected to be fully integrated into the state’s main grid by the end of the week, just as work begins on the AUD 625 million ($415 million) second stage which will provide four times as much storage capacity.

The 800 MWh second stage of the battery energy storage system, which is scheduled to be completed by late 2024, is being built on a three-hectare plot adjacent to the first grid-scale battery established at the site of the decommissioned Kwinana Power Station about 30 kilometres south of Perth.

Synergy, which will operate and manage the battery energy storage system, said the new battery will comprise 288 shipping container-sized battery modules and 72 inverter units that will employ new-generation technology to support grid stability by storing electricity when demand is lowest and delivering it back into the grid during peak times, providing vital system security for the South West Interconnected System (SWIS).

West Australian Premier Roger Cook said the battery will serve as the “infrastructure of future”, playing a major role in the state’s energy transformation with WA’s state-owned coal power stations to be retired by 2030.

It is expected the battery will support the integration of more renewable energy into the grid, smooth fluctuations in demand and renewable energy supply and substantially contribute to grid security and stability.

The West Australian government has allocated AUD 2.8 billion in its latest budget for renewable energy infrastructure, including a 500 MW/2,000 MWh battery energy storage system to be built near the coal town of Collie in the state’s southwest. The development application for the Collie big battery is expected to be submitted later this year.

The West Australian government has estimated that the SWIS may need about 50 GW of new renewable electricity and storage infrastructure to support increased demand over the next 20 years.